So if we report to this sketch, the base of the cone is the left circle, whose radius is 3 (and whose perimeter is . The right part will be a quarter of circle, let's say of radius P, and which corresponds to the height of the cone !

The perimeter of the complete circle corresponding to the quarter circle is
Hence the perimeter of the quarter circle is

This perimeter corresponds to the perimeter of the right circle, so we have :

The volume of a cone is given by

So here, the area of the base, which is the area of a circle, radius 3, will be